This disclosure relates to methods of improving the rheology properties of divalent brine based fluids. The disclosure also relates to divalent brine based fluids having improved rheology and multifunctional properties and methods of using such fluids.
Divalent brines are mainly used to prepare drill-in fluids. Drill-in fluids are designed to be essentially non-damaging to the producing formation. Ideally, drill-in fluids can also provide superior hole cleaning property, allow easy clean-up, and are cost effective.
In conventional drill-in fluids, organic polymers are often used to control rheological and fluid loss properties. While organic polymers are normally stable in fresh water, they can rapidly degrade in a divalent salt environment resulting in system instability, especially at an elevated temperature. Accordingly, the art would be receptive to alternative additives that are effective to enhance the rheological profile of a divalent brine based fluid at elevated temperatures. It would be a further advantage if such additives could also enhance fluid loss control or lubricity of the divalent brine based fluid.